According to maximum achievable control technology (MACT) and European regulations, emerging emission standards will affect most manufacturing areas containing operational vents to atmosphere. A cost-effective strategy for treating hazardous flammable solvent emissions is to manifold operational vessel vents together to one emission control device. However, in the unexpected event of a flammable solvent ignition, there is a possibility of fire or deflagration propagation, which could potentially destroy any or all the devices connected in the vent system. Therefore, fire and explosion protection schemes must be in place to minimize potential consequences of a fire or explosion. Prior art includes an explosion diverter or backflash interrupter to prevent flames from propagating from one piece of equipment to another through the interconnecting piping.
The basic principle of operation of a typical device as described above is that a deflagration is vented in a different flow direction than the normal flow path. Due to the inertia of the fast flow caused by the deflagration, the flow will tend to maintain its direction upward rather than making the hard degree turn as when the vessel emission flow velocity is low during normal conditions. When the high-speed deflagration flame continues upward, it pushes open either a hinged cover or bursts a rupture disc located at the top of the diverter, allowing the flame to be released to the atmosphere. The limitations placed on the existing device are that it can only be used in processes with a combustible dust with very low concentrations. The operating pressure is limited to 0.1 barg (1.5 psig) due to the pressure setting of the relief device required for approval.
Another device to prevent propagation during a deflagration is the explosion isolation valve. There are high-speed sensors installed on both sides of the isolation valve to detect a high rate of pressure rise in the pipeline and then close the valve before the deflagration can pass through. This is an expensive scheme with no guarantee that the valve will close before the deflagration or flame passes through.
Therefore, a need persists in the art for an explosion protection venting system having a flame front diverter element that diverts deflagration along an alternate path and away from the normal flow path that avoids a disastrous impact to nearby structures.